The general aim of this subproject is the discovery and analysis of variable sequences by new methods. The initial search will be made on a panel of DNA's from individuals chosen to represent the world variation. Major methods and strategies include: 1) Unique sequences, originating from sequence tagged sites (STS's) already available for the Y chromosomes, and new ones to be obtained from Y chromosome YACs will be screened for sequence variation by direct sequencing, following the method summarized in the progress report and the research design below. 2) A search of highly variable sequences will be set up using new mismatch repair methods to be developed. They will be developed for all chromosomes, and also for the Y and X chromosome. 3) We plan to increase our collection of data on mitochondrial DNA variation of the 2 segments of the D-loop, on populations of the circum- mediterranean Basin, including Caucasoids and mixed populations of North and East Africa, and Chinese ethnic populations. 4) We plan to continue obtaining, extending and analyzing results with microsatellites, with a variety of new methods. Problems of evolutionary importance based on mutation rates, natural selection, optimal genetic distances will be paid special attention. We are also interested in carefully testing methods lending themselves for use in less well equipped laboratories which do not have access to radioisotopes or expensive equipment and reagents, so that studies of Human Genome Diversity can be carried out in all countries of the world and contribute efficiently to technology transfer to the South (the Third World).